diff --git a/modules/openapi-generator/src/test/resources/3_0/java/petstore-with-fake-endpoints-models-for-testing-okhttp-gson.yaml b/modules/openapi-generator/src/test/resources/3_0/java/petstore-with-fake-endpoints-models-for-testing-okhttp-gson.yaml
index f4c8dad31d2..4d44d00b329 100644
--- a/modules/openapi-generator/src/test/resources/3_0/java/petstore-with-fake-endpoints-models-for-testing-okhttp-gson.yaml
+++ b/modules/openapi-generator/src/test/resources/3_0/java/petstore-with-fake-endpoints-models-for-testing-okhttp-gson.yaml
@@ -2600,6 +2600,8 @@ components:
     Scalar:
       description: Values of scalar type
       oneOf:
+        - type: string
+          format: uuid
         - type: string
           maxLength: 1089
         - type: number
@@ -2607,6 +2609,8 @@ components:
     ScalarAnyOf:
       description: Values of scalar type using anyOf
       anyOf:
+        - type: string
+          format: uuid
         - type: string
           maxLength: 1089
         - type: number
diff --git a/samples/client/petstore/java/okhttp-gson/api/openapi.yaml b/samples/client/petstore/java/okhttp-gson/api/openapi.yaml
index c0ff5254e61..f21b84165a8 100644
--- a/samples/client/petstore/java/okhttp-gson/api/openapi.yaml
+++ b/samples/client/petstore/java/okhttp-gson/api/openapi.yaml
@@ -2715,7 +2715,7 @@ components:
       description: Value object
       example:
         name: variable_1
-        value: Scalar
+        value: 046b6c7f-0b8a-43b9-b35d-6489e6daee91
       properties:
         name:
           example: variable_1
@@ -2732,12 +2732,16 @@ components:
     Scalar:
       description: Values of scalar type
       oneOf:
+      - format: uuid
+        type: string
       - maxLength: 1089
         type: string
       - type: number
       - type: boolean
     ScalarAnyOf:
       anyOf:
+      - format: uuid
+        type: string
       - maxLength: 1089
         type: string
       - type: number
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Scalar.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Scalar.java
index 2a36043d6c4..c1d9002d5c3 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Scalar.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Scalar.java
@@ -15,6 +15,7 @@ package org.openapitools.client.model;
 
 import java.util.Objects;
 import java.math.BigDecimal;
+import java.util.UUID;
 
 
 
@@ -63,6 +64,7 @@ public class Scalar extends AbstractOpenApiSchema {
                 return null; // this class only serializes 'Scalar' and its subtypes
             }
             final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
+            final TypeAdapter<UUID> adapterUUID = gson.getDelegateAdapter(this, TypeToken.get(UUID.class));
             final TypeAdapter<String> adapterString = gson.getDelegateAdapter(this, TypeToken.get(String.class));
             final TypeAdapter<BigDecimal> adapterBigDecimal = gson.getDelegateAdapter(this, TypeToken.get(BigDecimal.class));
             final TypeAdapter<Boolean> adapterBoolean = gson.getDelegateAdapter(this, TypeToken.get(Boolean.class));
@@ -75,6 +77,12 @@ public class Scalar extends AbstractOpenApiSchema {
                         return;
                     }
 
+                    // check if the actual instance is of the type `UUID`
+                    if (value.getActualInstance() instanceof UUID) {
+                        JsonElement element = adapterUUID.toJsonTree((UUID)value.getActualInstance());
+                        elementAdapter.write(out, element);
+                        return;
+                    }
                     // check if the actual instance is of the type `String`
                     if (value.getActualInstance() instanceof String) {
                         JsonPrimitive primitive = adapterString.toJsonTree((String)value.getActualInstance()).getAsJsonPrimitive();
@@ -93,7 +101,7 @@ public class Scalar extends AbstractOpenApiSchema {
                         elementAdapter.write(out, primitive);
                         return;
                     }
-                    throw new IOException("Failed to serialize as the type doesn't match oneOf schemas: BigDecimal, Boolean, String");
+                    throw new IOException("Failed to serialize as the type doesn't match oneOf schemas: BigDecimal, Boolean, String, UUID");
                 }
 
                 @Override
@@ -105,6 +113,18 @@ public class Scalar extends AbstractOpenApiSchema {
                     ArrayList<String> errorMessages = new ArrayList<>();
                     TypeAdapter actualAdapter = elementAdapter;
 
+                    // deserialize UUID
+                    try {
+                        // validate the JSON object to see if any exception is thrown
+                        UUID.fromString(jsonElement.getAsString());
+                        actualAdapter = adapterUUID;
+                        match++;
+                        log.log(Level.FINER, "Input data matches schema 'UUID'");
+                    } catch (Exception e) {
+                        // deserialization failed, continue
+                        errorMessages.add(String.format("Deserialization for UUID failed with `%s`.", e.getMessage()));
+                        log.log(Level.FINER, "Input data does not match schema 'UUID'", e);
+                    }
                     // deserialize String
                     try {
                         // validate the JSON object to see if any exception is thrown
@@ -173,6 +193,7 @@ public class Scalar extends AbstractOpenApiSchema {
     }
 
     static {
+        schemas.put("UUID", UUID.class);
         schemas.put("String", String.class);
         schemas.put("BigDecimal", BigDecimal.class);
         schemas.put("Boolean", Boolean.class);
@@ -186,12 +207,17 @@ public class Scalar extends AbstractOpenApiSchema {
     /**
      * Set the instance that matches the oneOf child schema, check
      * the instance parameter is valid against the oneOf child schemas:
-     * BigDecimal, Boolean, String
+     * BigDecimal, Boolean, String, UUID
      *
      * It could be an instance of the 'oneOf' schemas.
      */
     @Override
     public void setActualInstance(Object instance) {
+        if (instance instanceof UUID) {
+            super.setActualInstance(instance);
+            return;
+        }
+
         if (instance instanceof String) {
             super.setActualInstance(instance);
             return;
@@ -207,14 +233,14 @@ public class Scalar extends AbstractOpenApiSchema {
             return;
         }
 
-        throw new RuntimeException("Invalid instance type. Must be BigDecimal, Boolean, String");
+        throw new RuntimeException("Invalid instance type. Must be BigDecimal, Boolean, String, UUID");
     }
 
     /**
      * Get the actual instance, which can be the following:
-     * BigDecimal, Boolean, String
+     * BigDecimal, Boolean, String, UUID
      *
-     * @return The actual instance (BigDecimal, Boolean, String)
+     * @return The actual instance (BigDecimal, Boolean, String, UUID)
      */
     @SuppressWarnings("unchecked")
     @Override
@@ -222,6 +248,17 @@ public class Scalar extends AbstractOpenApiSchema {
         return super.getActualInstance();
     }
 
+    /**
+     * Get the actual instance of `UUID`. If the actual instance is not `UUID`,
+     * the ClassCastException will be thrown.
+     *
+     * @return The actual instance of `UUID`
+     * @throws ClassCastException if the instance is not `UUID`
+     */
+    public UUID getUUID() throws ClassCastException {
+        return (UUID)super.getActualInstance();
+    }
+
     /**
      * Get the actual instance of `String`. If the actual instance is not `String`,
      * the ClassCastException will be thrown.
@@ -265,6 +302,14 @@ public class Scalar extends AbstractOpenApiSchema {
         // validate oneOf schemas one by one
         int validCount = 0;
         ArrayList<String> errorMessages = new ArrayList<>();
+        // validate the json string with UUID
+        try {
+            UUID.fromString(jsonElement.getAsString());
+            validCount++;
+        } catch (Exception e) {
+            errorMessages.add(String.format("Deserialization for UUID failed with `%s`.", e.getMessage()));
+            // continue to the next one
+        }
         // validate the json string with String
         try {
             if (!jsonElement.getAsJsonPrimitive().isString()) {
@@ -296,7 +341,7 @@ public class Scalar extends AbstractOpenApiSchema {
             // continue to the next one
         }
         if (validCount != 1) {
-            throw new IOException(String.format("The JSON string is invalid for Scalar with oneOf schemas: BigDecimal, Boolean, String. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonElement.toString()));
+            throw new IOException(String.format("The JSON string is invalid for Scalar with oneOf schemas: BigDecimal, Boolean, String, UUID. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonElement.toString()));
         }
     }
 
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ScalarAnyOf.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ScalarAnyOf.java
index a79de259e94..92d13892493 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ScalarAnyOf.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ScalarAnyOf.java
@@ -15,6 +15,7 @@ package org.openapitools.client.model;
 
 import java.util.Objects;
 import java.math.BigDecimal;
+import java.util.UUID;
 
 
 
@@ -63,6 +64,7 @@ public class ScalarAnyOf extends AbstractOpenApiSchema {
                 return null; // this class only serializes 'ScalarAnyOf' and its subtypes
             }
             final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
+            final TypeAdapter<UUID> adapterUUID = gson.getDelegateAdapter(this, TypeToken.get(UUID.class));
             final TypeAdapter<String> adapterString = gson.getDelegateAdapter(this, TypeToken.get(String.class));
             final TypeAdapter<BigDecimal> adapterBigDecimal = gson.getDelegateAdapter(this, TypeToken.get(BigDecimal.class));
             final TypeAdapter<Boolean> adapterBoolean = gson.getDelegateAdapter(this, TypeToken.get(Boolean.class));
@@ -75,6 +77,12 @@ public class ScalarAnyOf extends AbstractOpenApiSchema {
                         return;
                     }
 
+                    // check if the actual instance is of the type `UUID`
+                    if (value.getActualInstance() instanceof UUID) {
+                        JsonElement element = adapterUUID.toJsonTree((UUID)value.getActualInstance());
+                        elementAdapter.write(out, element);
+                        return;
+                    }
                     // check if the actual instance is of the type `String`
                     if (value.getActualInstance() instanceof String) {
                         JsonPrimitive primitive = adapterString.toJsonTree((String)value.getActualInstance()).getAsJsonPrimitive();
@@ -93,7 +101,7 @@ public class ScalarAnyOf extends AbstractOpenApiSchema {
                         elementAdapter.write(out, primitive);
                         return;
                     }
-                    throw new IOException("Failed to serialize as the type doesn't match anyOf schemas: BigDecimal, Boolean, String");
+                    throw new IOException("Failed to serialize as the type doesn't match anyOf schemas: BigDecimal, Boolean, String, UUID");
                 }
 
                 @Override
@@ -104,6 +112,19 @@ public class ScalarAnyOf extends AbstractOpenApiSchema {
                     ArrayList<String> errorMessages = new ArrayList<>();
                     TypeAdapter actualAdapter = elementAdapter;
 
+                    // deserialize UUID
+                    try {
+                        // validate the JSON object to see if any exception is thrown
+                        UUID.fromString(jsonElement.getAsString());
+                        actualAdapter = adapterUUID;
+                        ScalarAnyOf ret = new ScalarAnyOf();
+                        ret.setActualInstance(actualAdapter.fromJsonTree(jsonElement));
+                        return ret;
+                    } catch (Exception e) {
+                        // deserialization failed, continue
+                        errorMessages.add(String.format("Deserialization for UUID failed with `%s`.", e.getMessage()));
+                        log.log(Level.FINER, "Input data does not match schema 'UUID'", e);
+                    }
                     // deserialize String
                     try {
                         // validate the JSON object to see if any exception is thrown
@@ -169,6 +190,7 @@ public class ScalarAnyOf extends AbstractOpenApiSchema {
     }
 
     static {
+        schemas.put("UUID", UUID.class);
         schemas.put("String", String.class);
         schemas.put("BigDecimal", BigDecimal.class);
         schemas.put("Boolean", Boolean.class);
@@ -182,12 +204,17 @@ public class ScalarAnyOf extends AbstractOpenApiSchema {
     /**
      * Set the instance that matches the anyOf child schema, check
      * the instance parameter is valid against the anyOf child schemas:
-     * BigDecimal, Boolean, String
+     * BigDecimal, Boolean, String, UUID
      *
      * It could be an instance of the 'anyOf' schemas.
      */
     @Override
     public void setActualInstance(Object instance) {
+        if (instance instanceof UUID) {
+            super.setActualInstance(instance);
+            return;
+        }
+
         if (instance instanceof String) {
             super.setActualInstance(instance);
             return;
@@ -203,14 +230,14 @@ public class ScalarAnyOf extends AbstractOpenApiSchema {
             return;
         }
 
-        throw new RuntimeException("Invalid instance type. Must be BigDecimal, Boolean, String");
+        throw new RuntimeException("Invalid instance type. Must be BigDecimal, Boolean, String, UUID");
     }
 
     /**
      * Get the actual instance, which can be the following:
-     * BigDecimal, Boolean, String
+     * BigDecimal, Boolean, String, UUID
      *
-     * @return The actual instance (BigDecimal, Boolean, String)
+     * @return The actual instance (BigDecimal, Boolean, String, UUID)
      */
     @SuppressWarnings("unchecked")
     @Override
@@ -218,6 +245,17 @@ public class ScalarAnyOf extends AbstractOpenApiSchema {
         return super.getActualInstance();
     }
 
+    /**
+     * Get the actual instance of `UUID`. If the actual instance is not `UUID`,
+     * the ClassCastException will be thrown.
+     *
+     * @return The actual instance of `UUID`
+     * @throws ClassCastException if the instance is not `UUID`
+     */
+    public UUID getUUID() throws ClassCastException {
+        return (UUID)super.getActualInstance();
+    }
+
     /**
      * Get the actual instance of `String`. If the actual instance is not `String`,
      * the ClassCastException will be thrown.
@@ -260,6 +298,14 @@ public class ScalarAnyOf extends AbstractOpenApiSchema {
     public static void validateJsonElement(JsonElement jsonElement) throws IOException {
         // validate anyOf schemas one by one
         ArrayList<String> errorMessages = new ArrayList<>();
+        // validate the json string with UUID
+        try {
+            UUID.fromString(jsonElement.getAsString());
+            return;
+        } catch (Exception e) {
+            errorMessages.add(String.format("Deserialization for UUID failed with `%s`.", e.getMessage()));
+            // continue to the next one
+        }
         // validate the json string with String
         try {
             if (!jsonElement.getAsJsonPrimitive().isString()) {
@@ -290,7 +336,7 @@ public class ScalarAnyOf extends AbstractOpenApiSchema {
             errorMessages.add(String.format("Deserialization for Boolean failed with `%s`.", e.getMessage()));
             // continue to the next one
         }
-        throw new IOException(String.format("The JSON string is invalid for ScalarAnyOf with anyOf schemas: BigDecimal, Boolean, String. no class match the result, expected at least 1. Detailed failure message for anyOf schemas: %s. JSON: %s", errorMessages, jsonElement.toString()));
+        throw new IOException(String.format("The JSON string is invalid for ScalarAnyOf with anyOf schemas: BigDecimal, Boolean, String, UUID. no class match the result, expected at least 1. Detailed failure message for anyOf schemas: %s. JSON: %s", errorMessages, jsonElement.toString()));
     }
 
     /**